Method and system of doppler correction for mobile communications systems
First Claim
1. A method of estimating a Doppler offset of a signal, comprising the steps of:
- receiving a Doppler effected signal comprising a preamble signal;
generating a delayed preamble signal based on the preamble signal;
multiplying the preamble signal by the delayed preamble signal to generate an in-phase preamble signal;
filtering the in-phase preamble signal to generate a substantially constant in-phase preamble signal;
accumulating a plurality of samples of the substantially constant in-phase preamble signal;
generating a phase-shifted preamble signal based on the preamble signal;
multiplying the phase-shifted preamble signal by the delayed preamble signal to generate an out-of-phase preamble signal;
filtering the out-of-phase preamble signal to generate a substantially constant out-of-phase preamble signal;
accumulating a plurality of samples of the substantially constant out-of-phase preamble signal; and
normalizing a sum of the in-phase preamble samples and a sum of the out-of-phase preamble samples relative to each other to generate an in-phase Doppler estimator and a out-of-phase Doppler estimator.
1 Assignment
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Accused Products
Abstract
Doppler correction system and method comprising receiving a Doppler effected signal comprising a preamble signal (32). A delayed preamble signal (48) may be generated based on the preamble signal (32). The preamble signal (32) may be multiplied by the delayed preamble signal (48) to generate an in-phase preamble signal (60). The in-phase preamble signal (60) may be filtered to generate a substantially constant in-phase preamble signal (62). A plurality of samples of the substantially constant in-phase preamble signal (62) may be accumulated. A phase-shifted signal (76) may also be generated based on the preamble signal (32). The phase-shifted signal (76) may be multiplied by the delayed preamble signal (48) to generate an out-of-phase preamble signal (80). The out-of-phase preamble signal (80) may be filtered to generate a substantially constant out-of-phase preamble signal (82). A plurality of samples of the substantially constant out-of-phase signal (82) may be accumulated. A sum of the in-phase preamble samples and a sum of the out-of-phase preamble samples may be normalized relative to each other to generate an in-phase Doppler estimator (92) and an out-of-phase Doppler estimator (94).
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Citations
45 Claims
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1. A method of estimating a Doppler offset of a signal, comprising the steps of:
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receiving a Doppler effected signal comprising a preamble signal; generating a delayed preamble signal based on the preamble signal; multiplying the preamble signal by the delayed preamble signal to generate an in-phase preamble signal; filtering the in-phase preamble signal to generate a substantially constant in-phase preamble signal; accumulating a plurality of samples of the substantially constant in-phase preamble signal; generating a phase-shifted preamble signal based on the preamble signal; multiplying the phase-shifted preamble signal by the delayed preamble signal to generate an out-of-phase preamble signal; filtering the out-of-phase preamble signal to generate a substantially constant out-of-phase preamble signal; accumulating a plurality of samples of the substantially constant out-of-phase preamble signal; and normalizing a sum of the in-phase preamble samples and a sum of the out-of-phase preamble samples relative to each other to generate an in-phase Doppler estimator and a out-of-phase Doppler estimator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of correcting for a Doppler offset of a signal, comprising the steps of:
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receiving a Doppler effected signal comprising a preamble signal and a data signal; generating a delayed preamble signal based on the preamble signal; multiplying the preamble signal by the delayed preamble signal to generate an in-phase preamble signal; filtering the in-phase preamble signal to generate a substantially constant in-phase preamble signal; accumulating a plurality of samples of the substantially constant in-phase preamble signal; generating a phase-shifted preamble signal based on the preamble signal; multiplying the phase-shifted preamble signal by the delayed preamble signal to generate an out-of-phase preamble signal; filtering the out-of-phase preamble signal to generate a substantially constant out-of-phase preamble signal; accumulating a plurality of samples of the substantially constant out-of-phase preamble signal; normalizing a sum of the in-phase preamble samples and a sum of the out-of-phase preamble samples relative to each other to generate an in-phase Doppler estimator and a out-of-phase Doppler estimator; generating a delayed data signal based on the data signal; multiplying the data signal by the delayed data signal to generate an in-phase data signal; multiplying the in-phase data signal by the in-phase Doppler estimator to generate a Doppler corrected in-phase data signal; generating a phase-shifted data signal based on the data signal; multiplying the phase-shifted data signal by the delayed data signal to generate an out-of-phase data signal; multiplying the out-of-phase data signal by the out-of-phase Doppler estimator to generate a Doppler corrected out-of-phase data signal; and combining the Doppler corrected in-phase data signal and the Doppler corrected out-of-phase data signal to generate a Doppler corrected data signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A mobile communications system, comprising:
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a first object comprising a transmitter to transmit a predefined preamble signal with a data signal; a second object moving relative to the first object, the second comprising; a receiver to receive the transmitted preamble signal and the data signal; a Doppler estimation circuit comprising; a delay channel coupled to the receiver to generate a delayed preamble signal based on the preamble signal; an in-phase channel coupled to the receiver and the delay channel, comprising; a first multiplier junction to multiply the preamble signal by the delayed preamble signal to generate an in-phase preamble signal; a first filter to generate a substantially constant in-phase preamble signal; a first accumulator to obtain a plurality of samples of the substantially constant in-phase preamble signal; an out-of-phase channel coupled to the receiver and the delay channel, comprising; a transform to generate a phase-shifted preamble signal based on the preamble signal; a second multiplier junction to multiply the phase-shifted preamble signal by the delayed preamble signal to generate an out-of-phase preamble signal; a second filter to generate a substantially constant out-of-phase preamble signal; an second accumulator to obtain a plurality of samples of the substantially constant out-of-phase preamble signal; and a normalizer to normalize a sum of the in-phase preamble samples and a sum of the out-of-phase preamble samples relative to each other to generate an in-phase Doppler estimator and an out-of-phase Doppler estimator. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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Specification